Plasma resonances in a microwave-driven microdischarge

Xue, Jiang; Urdahl, Randall; Cooley, James

doi:10.1063/1.3681146

Cited by 14 publications

(11 citation statements)

References 7 publications

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“…Thence, the bulk plasma density n bulk can be calculated 8:3 Â 10 20 m -3 approximately. It should be mentioned that although this density value is consistent with previous studies reported from the similar lowerpower argon microwave plasma jets driven by continues microwave power in ambient air, [3][4][5][6][7][8][9][10][11][12][13][14][15][16]32 the actual plasma density of the pulsed plasma jet is lower than this value, due to the average power absorbed by the electrons lower largely in pulsed discharge with the same peak power amplitude.…”

Section: Experimental Summarysupporting

confidence: 81%

“…[3][4][5][6][7] Especially for several applications, such as medical instrument sterilization, metal surface nitriding, and high-velocity fuel ignition and combustion, atmospheric microwave plasma devices have shown its potential advantages in industrial applications. [8][9][10][11] There are four types of low-power microwave resonators: coaxial transmission line resonators (CTLR), 3 microstrip line resonators, 4 surfatron launchers, 12 and surface-wave plasma jets, [13][14][15] which are with different characteristics and thereafter are constructed for satisfying different application demands. Generally, these microwave resonators are excited by continuous microwave power supplies.…”

mentioning

confidence: 99%

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Self-consistent fluid modeling and simulation on a pulsed microwave atmospheric-pressure argon plasma jet

Chen

Yin

Ming-gong

et al. 2014

Journal of Applied Physics

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In present study, a pulsed lower-power microwave-driven atmospheric-pressure argon plasma jet has been introduced with the type of coaxial transmission line resonator. The plasma jet plume is with room air temperature, even can be directly touched by human body without any hot harm. In order to study ionization process of the proposed plasma jet, a self-consistent hybrid fluid model is constructed in which Maxwell's equations are solved numerically by finite-difference time-domain method and a fluid model is used to study the characteristics of argon plasma evolution. With a Guass type input power function, the spatio-temporal distributions of the electron density, the electron temperature, the electric field, and the absorbed power density have been simulated, respectively. The simulation results suggest that the peak values of the electron temperature and the electric field are synchronous with the input pulsed microwave power but the maximum quantities of the electron density and the absorbed power density are lagged to the microwave power excitation. In addition, the pulsed plasma jet excited by the local enhanced electric field of surface plasmon polaritons should be the discharge mechanism of the proposed plasma jet.

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Section: Experimental Summarysupporting

confidence: 81%

mentioning

confidence: 99%

Self-consistent fluid modeling and simulation on a pulsed microwave atmospheric-pressure argon plasma jet

Chen

Yin

Ming-gong

et al. 2014

Journal of Applied Physics

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“…The small size of the low-pressure microplasma devices, typically a few hundred microns, motivates the use of high excitation frequencies to limit the rate of loss of electrons and ions by drift in the electric field. In one configuration, a split-ring resonator operated at 2.45 GHz is used to create a large voltage across an electrode gap of a few hundred microns [7][8][9]. The use of arrays of split ring resonators to produce high pressure (up to atmospheric) microplasmas has been demonstrated by Hopwood et al [3,10].…”

Section: Introductionmentioning

confidence: 99%

Properties of microplasmas excited by microwaves for VUV photon sources

Cooley

Urdahl

Xue

et al. 2015

Plasma Sources Sci. Technol.

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Microplasma sources typically take advantage of pd (pressure × size) scaling by increasing pressure to operate at dimensions as small as tens of microns. In many applications, low pressure operation is desirable, which makes miniaturization difficult. In this paper, the characteristics of low pressure microplasma sources excited by microwave power are discussed based on results from experimental and computational studies. The intended application is production of VUV radiation for chemical analysis, and so emphasis in this study is on the production of resonant excited states of rare gases and radiation transport. The systems of interest operate at a few to 10 Torr in Ar and He/Ar mixtures with cavity dimensions of hundreds of microns to 1 mm. Power deposition is a few watts which produces fractional ionization of about 0.1%. We found that production of VUV radiation from argon microplasmas at 104.8 nm and 106.7 nm saturates as a function of power deposition due to a quasi-equilibrium that is established between the electron temperature (that is not terribly sensitive to power deposition) and the population of the Ar(4s) manifold.

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“…The series resonance occurs at a lower frequency related to the plasma frequency through a geometric factor involving the sheath thickness (s) and plasma length (L), x $ x p ffiffiffiffiffiffiffi s=L p . These resonant behaviors of the plasma have been intensively investigated over the years [3][4][5][6][7][8][9] (a brief chronological review is made in Ref. 3).…”

Section: Introductionmentioning

confidence: 99%

Modeling of microplasmas from GHz to THz

Gregório

Hoskinson

Hopwood

2015

Journal of Applied Physics

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We present a study of atmospheric-pressure microdischarges sustained over a wide range of continuous excitation frequencies. A fluid model is used to describe the spatial and temporal evolution of the plasma properties within a 200 μm discharge gap. At 0.5 GHz, the behavior is similar to a typical rf collisional discharge. As frequency increases at constant power density, we observe a decrease in the discharge voltage from greater than 100 V to less than 10 V. A minimum of the voltage amplitude is attained when electron temporal inertia delays the discharge current to be in phase with the applied voltage. Above this frequency, the plasma develops resonant regions where the excitation frequency equals the local plasma frequency. In these volumes, the instantaneous quasi-neutrality is perturbed and intense internal currents emerge ensuring a low voltage operation range. This enhanced plasma heating mechanism vanishes when the excitation frequency is larger than the local plasma frequency everywhere in the plasma volume. For a typical peak electron density of 5×1020 m−3, this condition corresponds to ∼0.2 THz. Beyond the plasma frequency, the discharge performs like a low loss dielectric and an increasingly large voltage is necessary to preserve a constant absorbed power.

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Plasma resonances in a microwave-driven microdischarge

Cited by 14 publications

References 7 publications

Self-consistent fluid modeling and simulation on a pulsed microwave atmospheric-pressure argon plasma jet

Self-consistent fluid modeling and simulation on a pulsed microwave atmospheric-pressure argon plasma jet

Properties of microplasmas excited by microwaves for VUV photon sources

Modeling of microplasmas from GHz to THz

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